Venoms are complex mixtures of compounds. Local and systemic effects following envenomation are the result of the combined effects of these venom components. Although antivenoms are presently available for most North American poisonous animals, this type of therapy can itself cause serious problems. Knowledge of the manner in which individual venom components exert their effect is necessary before successful and specific treatment of envenomation can be accomplished. Perhaps more importantly, purified venom components could potentially be used as drugs or as models for drugs. The few individual venom toxins which have been isolated have proven to be highly specific in their ability to disrupt certain biological processes. Unfortunately, the apparently simple process of separating a venom into its constitutents and determining the mode of action of these venom components at the molecular level has been hampered by the lack of fractionation and assay techniques. The immediate goal of the proposed research is the development of such techniques for venoms of North American snakes of the family Crotalidae and of the brown recluse spider, Loxosceles reclusa. Long range goals are the characterization of highly purified venom components as to structure and function and the preliminary evaluation of their potential therapeutic use.